The present invention is directed to liquid scintillation devices and, more particularly, is directed to a light seal mechanism for use in a liquid scintillation device.
In the normal operation of liquid scintillation, a plurality of sample carrying vials which include radioactive material are transferred sequentially into a shielded detector or counting chamber wherein light flashes or scintillations produced by photons being emitted from the radioactive samples can be reliaby detected by photomultiplier tubes or other sensing means in the detector chamber. To achieve accurate measurement the counting chamber must be properly secured and sealed to prevent the entry of any exterior environment. The entry of any exterior light would affect the sensitive and accurate counting done in the detector chamber.
Therefore, the entry port or passageway to the detector chamber must have some type of mechanism to properly seal the chamber while the counting operation is occurring with the particular sample carrying vial in the chamber.
Some prior approaches have been utilized, such as shown in U.S. Pat. No. 4,220,855 wherein a rotatable ring member or cylindrical member is designed to rotate and slip beneath the bottom of the sample vial, once it is in the chamber, and seal the passageway. The system appears to be somewhat complicated and may result in possible jamming when moving between the vial and the elevator mechanism.
Other prior art scintillation counters having means for excluding ambient light from the counting chamber are disclosed in U.S. Pat. Nos. 3,270,202 and 3,163,756 which are discussed in the above referenced U.S. Pat. No. 4,220,855.
It is important with respect to the provision of a light seal for use in conjunction with a counter chamber that the mechanism be not only simplified in its operation, but also reliable in its operation. It should be noted that the light seal mechanism will be operated repetitively numerous times while a group of sample containing vials are automatically sequenced into the detector chamber for measurement.